// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**
 * Javascript helper function for IMS Content Package module.
 *
 * @package   mod-imscp
 * @copyright 2009 Petr Skoda (http://skodak.org)
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

M.mod_imscp = {};

M.mod_imscp.init = function(Y) {

    var imscp_layout_widget;
    var imscp_current_node;
    var imscp_buttons = [];
    var imscp_bloody_labelclick = false;
    var imscp_panel;

    Y.use('yui2-resize', 'yui2-dragdrop', 'yui2-container', 'yui2-button', 'yui2-layout', 'yui2-treeview', 'yui2-json', 'yui2-event', function(Y) {

        var imscp_activate_item = function(node) {
            if (!node) {
                return;
            }
            imscp_current_node = node;
            imscp_current_node.highlight();

            var content = new YAHOO.util.Element('imscp_content');
            try {
                // first try IE way - it can not set name attribute later
                // and also it has some restrictions on DOM access from object tag
                var obj = document.createElement('<iframe id="imscp_object" src="'+node.href+'">');
            } catch (e) {
                var obj = document.createElement('object');
                obj.setAttribute('id', 'imscp_object');
                obj.setAttribute('type', 'text/html');
                obj.setAttribute('data', node.href);
            }
            var old = YAHOO.util.Dom.get('imscp_object');
            if (old) {
                content.replaceChild(obj, old);
            } else {
                content.appendChild(obj);
            }
            imscp_resize_frame();

            imscp_current_node.focus();
            imscp_fixnav();
        };

        /**
         * Enables/disables navigation buttons as needed.
         * @return void
         */
        var imscp_fixnav = function() {
            imscp_buttons[0].set('disabled', (imscp_skipprev(imscp_current_node) == null));
            imscp_buttons[1].set('disabled', (imscp_prev(imscp_current_node) == null));
            imscp_buttons[2].set('disabled', (imscp_up(imscp_current_node) == null));
            imscp_buttons[3].set('disabled', (imscp_next(imscp_current_node) == null));
            imscp_buttons[4].set('disabled', (imscp_skipnext(imscp_current_node) == null));
        };


        var imscp_resize_layout = function(alsowidth) {
            if (alsowidth) {
                var layout = YAHOO.util.Dom.get('imscp_layout');
                layout.style.width = '500px';
                var newwidth = imscp_get_htmlelement_size('content', 'width');
                if (newwidth > 500) {
                    layout.style.width = newwidth+'px';
                }
            }
            var pageheight = imscp_get_htmlelement_size('page', 'height');
            var layoutheight = imscp_get_htmlelement_size(imscp_layout_widget, 'height');
            var newheight = layoutheight + parseInt(YAHOO.util.Dom.getViewportHeight()) - pageheight - 20;
            if (newheight > 400) {
                imscp_layout_widget.setStyle('height', newheight+'px');
            }
            imscp_layout_widget.render();
            imscp_resize_frame();

            imscp_panel.align('bl', 'bl');
        };

        var imscp_get_htmlelement_size = function(el, prop) {
            var val = YAHOO.util.Dom.getStyle(el, prop);
            if (val == 'auto') {
                if (el.get) {
                    el = el.get('element'); // get real HTMLElement from YUI element
                }
                val = YAHOO.util.Dom.getComputedStyle(YAHOO.util.Dom.get(el), prop);
            }
            return parseInt(val);
        };

        var imscp_resize_frame = function() {
            var obj = YAHOO.util.Dom.get('imscp_object');
            if (obj) {
                var content = imscp_layout_widget.getUnitByPosition('center').get('wrap');
                obj.style.width = (content.offsetWidth - 6)+'px';
                obj.style.height = (content.offsetHeight - 10)+'px';
            }
        };


        var imscp_up = function(node) {
            if (node.depth > 0) {
                return node.parent;
            }
            return null;
        };

        var imscp_lastchild = function(node) {
            if (node.children.length) {
                return imscp_lastchild(node.children[node.children.length-1]);
            } else {
                return node;
            }
        };

        var imscp_prev = function(node) {
            if (node.previousSibling && node.previousSibling.children.length) {
                return imscp_lastchild(node.previousSibling);
            }
            return imscp_skipprev(node);
        };

        var imscp_skipprev = function(node) {
            if (node.previousSibling) {
                return node.previousSibling;
            } else if (node.depth > 0) {
                return node.parent;
            }
            return null;
        };

        var imscp_next = function(node) {
            if (node.children.length) {
                return node.children[0];
            }
            return imscp_skipnext(node);
        };

        var imscp_skipnext = function(node) {
            if (node.nextSibling) {
                return node.nextSibling;
            } else if (node.depth > 0) {
                return imscp_skipnext(node.parent);
            }
            return null;
        };


        // layout
        YAHOO.widget.LayoutUnit.prototype.STR_COLLAPSE = M.str.moodle.hide;
        YAHOO.widget.LayoutUnit.prototype.STR_EXPAND = M.str.moodle.show;

        imscp_layout_widget = new YAHOO.widget.Layout('imscp_layout', {
            minWidth: 600,
            minHeight: 400,
            units: [
                { position: 'left', body: 'imscp_toc', header: M.str.imscp.toc, width: 250, resize: true, gutter: '2px 5px 5px 2px', collapse: true, minWidth:150},
                { position: 'center', body: '<div id="imscp_content"></div>', gutter: '2px 5px 5px 2px', scroll: true}
            ]
        });
        imscp_layout_widget.render();
        var left = imscp_layout_widget.getUnitByPosition('left');
        left.on('collapse', function() {
            imscp_resize_frame();
        });
        left.on('expand', function() {
            imscp_resize_frame();
        });

        // ugly resizing hack that works around problems with resizing of iframes and objects
        left._resize.on('startResize', function() {
            var obj = YAHOO.util.Dom.get('imscp_object');
            obj.style.display = 'none';
        });
        left._resize.on('endResize', function() {
            var obj = YAHOO.util.Dom.get('imscp_object');
            obj.style.display = 'block';
            imscp_resize_frame();
        });

        // TOC tree
        var tree = new YAHOO.widget.TreeView('imscp_tree');
        tree.singleNodeHighlight = true;
        tree.subscribe('labelClick', function(node) {
            imscp_activate_item(node);
            if (node.children.length) {
                imscp_bloody_labelclick = true;
            }
        });
        tree.subscribe('collapse', function(node) {
            if (imscp_bloody_labelclick) {
                imscp_bloody_labelclick = false;
                return false;
            }
        });
        tree.subscribe('expand', function(node) {
            if (imscp_bloody_labelclick) {
                imscp_bloody_labelclick = false;
                return false;
            }
        });
        tree.expandAll();
        tree.render();

        // navigation
        imscp_panel = new YAHOO.widget.Panel('imscp_navpanel', { visible:true, draggable:true, close:false,
                                                               context: ['page', 'bl', 'bl', ["windowScroll", "textResize", "windowResize"]], constraintoviewport:true} );
        imscp_panel.setHeader(M.str.imscp.navigation);

        //TODO: make some better&accessible buttons
        imscp_panel.setBody('<span id="imscp_nav"><button id="nav_skipprev">&lt;&lt;</button><button id="nav_prev">&lt;</button><button id="nav_up">^</button><button id="nav_next">&gt;</button><button id="nav_skipnext">&gt;&gt;</button></span>');
        imscp_panel.render();
        imscp_buttons[0] = new YAHOO.widget.Button('nav_skipprev');
        imscp_buttons[1] = new YAHOO.widget.Button('nav_prev');
        imscp_buttons[2] = new YAHOO.widget.Button('nav_up');
        imscp_buttons[3] = new YAHOO.widget.Button('nav_next');
        imscp_buttons[4] = new YAHOO.widget.Button('nav_skipnext');
        imscp_buttons[0].on('click', function(ev) {
            imscp_activate_item(imscp_skipprev(imscp_current_node));
        });
        imscp_buttons[1].on('click', function(ev) {
            imscp_activate_item(imscp_prev(imscp_current_node));
        });
        imscp_buttons[2].on('click', function(ev) {
            imscp_activate_item(imscp_up(imscp_current_node));
        });
        imscp_buttons[3].on('click', function(ev) {
            imscp_activate_item(imscp_next(imscp_current_node));
        });
        imscp_buttons[4].on('click', function(ev) {
            imscp_activate_item(imscp_skipnext(imscp_current_node));
        });
        imscp_panel.render();

        // finally activate the first item
        imscp_activate_item(tree.getRoot().children[0]);

        // resizing
        imscp_resize_layout(false);

        // fix layout if window resized
        window.onresize = function() {
            imscp_resize_layout(true);
        };
    });
};
